I think that might be a pretty good mechanism, all said and done. Someone acts in a way the community doesn't accept enough times they go dead, and then if they act acceptably they start getting people responding and participating to them as they come out of dead status. They only get attention, and positive attention, from acting responsibly.
I read with showdead=yes and it is nowhere near that description. In fact dead posts are not even that common on most articles. And most of the dead posts, while on average low quality, are very rarely hateful or anything like that.
Like many policies that might actually have an effect, I'm hesitant to say exactly how much it achieves without data comparing what it's like without it.
